The image on the left shows DRR damage in a field (yellowed plants are affected) while that on the right shows how the fungus affects the plants.
Photo: ©Devashish Chobe, ICRISAT

ICRISAT researchers identify genes to defend chickpea against dry root rot

Researchers at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) have identified a set of promising genes in chickpea that could play a key role in the plant's defence against dry root rot (DRR), a devastating fungal disease.

In their battle against dry root rot (DRR) of chickpea, a devastating fungal disease emerging as a major threat in India, researchers at ICRISAT have recently zeroed in on a few promising sets of genes that play a key role in the plant’s defence. The team, led by Dr Mamta Sharma, who in their previous findings had affirmed the role of abiotic stresses in DRR incidence, have now explained the phenomenon at the molecular level. The team have found the involvement of endochitinase and PR-3-type chitinase (CHI III) genes in delaying the progression of DRR.

DRR is caused by Rhizoctonia bataticola, a soil-borne fungus that kills plant tissues and uses the dead matter to sustain itself. Such pathogens are termed necrotrophic. R. bataticola is known to infect a wide range of plant species. While Fusarium wilt in chickpea has traditionally been the concern of plant health experts, DRR has emerged over the past decade as a major threat in the heart of India’s chickpea producing regions – the central and southern states.

Plants in low soil moisture and with high temperature are more susceptible to DRR


If the climate supports it, DRR can cause up to 75 per cent yield loss in chickpea. “Changing climatic conditions bring changes to plant-pathogen interactions, which may either work in the plant’s favour or work against it. We are seeing that with rising average temperature and changes to the rainfall patterns, DRR has emerged as a major concern for chickpea farming in India,” Sharma, a Principal Scientist who leads the Precision Phenotyping Cluster at ICRISAT, said while explaining the rationale behind the long-term study being conducted in collaboration with the research institutions of the Indian Council of Agricultural Research (ICAR). Sharma is the coordinator of the Centre of Excellence on Climate Change Research for Plant Protection at ICRISAT, where the study is being done.

In the most recent experiment, the findings of which were published in Frontiers in Plant Science, researchers underscored the importance of testing responses to multiple stresses in tandem. They studied DRR susceptibility in two cultivars (BG 212 and JG 11) in high soil moisture and low temperature conditions as well as in low soil moisture and high temperature conditions. The disease susceptibility was higher in the second set of conditions. They then proceeded to study the differential gene expression of several stress-responsive genes in chickpea.

“The significant overexpression of genes encoding for the enzymes endochitinase and PR-3-type chitinase implicated their role in the plant’s defence mechanism. We found these genes very active in the early stages of the disease, particularly under low soil moisture conditions, and have concluded that they contribute to delaying the progression,” said the study’s first author Sharath Chandran, a Senior Research Fellow at ICRISAT.

The authors hope their emerging insights into chickpea’s DRR defence mechanisms will pave the way for future research towards the development of management strategies that prevents this disease from assuming epidemic proportions.

For now, the findings of the study make a strong case for irrigating chickpea fields during the crucial flowering and pod development stages to arrest the progress of DRR post infection in order to mitigate severity and crop loss.

(ICRISAT/wi)

Reference:
Sharath Chandran et al.: Temperature and Soil Moisture Stress Modulate the Host Defense Response in Chickpea During Dry Root Rot Incidence; Frontiers in Plant Science, 04 June 2021 | https://doi.org/10.3389/fpls.2021.653265

For more information:
Centre of Excellence on Climate Change Research for Plant Protection at ICRISAT

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